a) Field of the Invention
This invention relates to optical interconnection apparatuses (optical circuit boards) for interconnecting optical elements, components and/or devices used in optical communications or optical information processing, such as optical elements, optical circuit packages and optical circuit devices, and also to fabrication process thereof.
b) Description of the Related Art
To permit interconnections between plural optical elements in an optical circuit package or optical interconnections between plural optical circuit packages or between optical circuit devices on each of which optical circuit packages are mounted, these optical elements, optical circuit packages and optical circuit devices are provided at terminals thereof with optical connectors to interconnect them together via optical fibers. As these optical fibers have to be arranged with slack in this case, it is a current practice that, on an optical circuit package or inside and/or on a back side of an optical circuit device, intricately routed lines of the optical fibers extend overlapping one another in the form of a bird""s nest and hence occupy a large space. For optical interconnection processes requiring such large space and substantial interconnecting labor for intricate routing as described above, simple methods have been proposed to solve these problems by routing optical fibers in a two-dimensional plane as desired. As is disclosed in JP 2,574,611 B, for example, it is proposed to use a sheet or base film with a pressure-sensitive adhesive coated thereon and to hold optical fibers in place by the pressure-sensitive adhesive.
According to these methods, the optical fibers held in place on the sheet or base film are strong against breakage by bending or the like owing to the arrangement of the sheet or base film, but the optical fibers located extending out from the sheet or base film are very fragile and are weak and easily broken by breaking such as bending. Especially at an edge of the sheet or base film, there is a significant difference in strength between the optical fibers held in place on the sheet or base film and the optical fibers located extending out from the sheet or base film, resulting in a problem that the optical fibers are easily broken in a vicinity of the edge of the sheet or base film when bent or otherwise stressed.
Especially, optical fibers located extending out from an optical interconnection apparatus require work such as polishing for the interconnection of a connector, assembling of the connector onto the optical fibers subsequent to the polishing, and interconnection to another optical apparatus or to a connector attached to the optical apparatus. During these work, stress is applied to end portions of the optical fibers, resulting in a problem that the optical fibers are easily broken at portions thereof located in the vicinity of an edge of a sheet or base film. Incidentally, it is proposed in JP 2,574,611 B to provide optical fibers with tabs at portions thereof, said portions being located extending out from a base film. These tabs, however, provides absolutely no solution to the breakage problem of the optical fibers which, when the optical fibers are bent, arises due to a difference in strength between inner portions of the optical fibers, said inner portions being held in place by the tabs on the edge of the base film, and outer portions of the optical fibers, said outer portions being located extending from the tabs.
This invention has been completed to solve the above-described problem of the conventional art. Described specifically, the present invention has as an object thereof the prevention of breakage of plural optical fibers in an optical interconnection apparatus in which the optical fibers extend overlapping one another as described above, which occurs when the optical fibers are bent or otherwise stressed during work such as endface polishing of the optical fibers for the interconnection of a connector, assembly of the connector onto the optical fibers after the endface polishing, and interconnection to another optical apparatus or to a connector attached to the optical apparatus, or during handling of the optical interconnection apparatus. It is therefore an object of the present invention to provide an optical interconnection apparatus, which provides optical fibers with strength in the vicinity of an edge of the optical interconnection apparatus and has excellent workability, and a fabrication process of the optical interconnection apparatus.
The present invention therefore provides a process for the fabrication of an optical interconnection apparatus in which plural optical fibers provided at ports thereof with end portions for optical interconnection are routed in a two-dimensional plane such that a routing pattern having at least one type of parts selected from overlapping parts, curved parts or fiber pitch change parts is formed and the end portions of the optical fibers, said end portions being located extending out from a main body of the optical interconnection apparatus, are protected by protective boots, which comprises:
forming an edge-dam member, which is provided with protruding portions for forming protective boots, along or in a vicinity of a peripheral edge of a base film for supporting the thus-routed optical fibers thereon; and
filling a resin material inside the edge-dam member such that a protective resin layer is formed to hold the optical fibers in place and the protective boots are formed on the end portions of the optical fibers.